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Delaying colonoscopy after positive FIT linked to higher CRC risk
Patients with a positive fecal immunochemical test who waited more than 10 months to undergo the required follow-up colonoscopy had a higher risk for colorectal cancer and a more advanced stage of disease at diagnosis compared with patients who underwent follow-up colonoscopy within a month, according to new research published in JAMA.
However, given the observational nature of the study, “further research is needed to assess whether this relationship is causal,” Douglas A. Corley, MD, PhD, of the division of research at Kaiser Permanente Northern California, and colleagues wrote.
Douglas A. Corley
Fecal immunochemical testing (FIT), endorsed by the U.S. Preventive Services Task Force, is becoming an increasingly common CRC screening method in the U.S., but there is insufficient evidence on how quickly a follow-up colonoscopy should be completed after a positive FIT result.
Aiming to determine if the time between a positive FIT result and follow-up colonoscopy is associated with CRC risk, Corley and colleagues performed a retrospective cohort study of 70,124 patients (median age, 61 years; range, 50-70 years; 52.7% men) who underwent colonoscopy at Kaiser Permanente from 2010 through 2014 after a positive FIT result.
Overall, 2,191 patients were diagnosed with CRC and 601 of them were diagnosed with advanced-stage disease. In addition, 27,176 patients underwent follow-up colonoscopy within 8 to 30 days, 24,644 at 2 months, 8,666 at 3 months, 5,251 at 4-6 months, 1,335 at 7 months to 9 months, 748 at 10 months to 12 months, and 747 at more than 12 months.
The investigators observed no significant differences in overall CRC risk nor in advanced-stage disease diagnosis among all patient groups screened between 8 days to 30 days and 7 months to 9 months. CRC cases ranged between 30 per 1,000 patients in the 8 to 30-day group and 43 per 1,000 patients in the 7- to 9-month group, and advanced-stage disease diagnoses ranged from eight to 13 per 1,000, respectively.
However, compared with patients who underwent colonoscopy within 8 days to 30 days, those who waited until 10 months to 12 months showed a significantly higher CRC risk, with 49 cases per 1,000 patients (OR = 1.48; 95% CI, 1.05-2.08), and also a significantly higher risk for advanced-stage disease at diagnosis, with 19 cases per 1,000 patients (OR = 1.97; 95% CI, 1.14-3.42). The risks were even higher for patients who waited longer than 12 months, with 76 CRC cases per 1,000 patients (OR = 2.25; 95% CI, 1.89-2.68) and 31 cases of advanced-stage disease at diagnosis (OR = 3.22; 95% CI, 2.44-4.25).
“There was a higher risk of stage II colorectal cancer at 7 to 9 months; of any colorectal cancer, advanced-stage disease, and stage II and IV colorectal cancer at 10 to 12 months; and of advanced adenomas, any colorectal cancer, advanced-stage disease, and stages II-IV colorectal cancer at more than 12 months,” Corley and colleagues wrote.
In a related editorial, Carolyn M. Rutter, PhD, of the RAND Corporation in Santa Monica, Calfornia, and John M. Inadomi, MD, of the University of Washington Medicine, Seattle, characterized these findings as reassuring, as they suggest “there is no immediate need to rush to have a colonoscopy after a positive FIT result.” However, the study shows that “longer time to follow-up will reduce the benefit of FIT, with detection of more cancers and more late-stage disease,” they added.
They concluded that “for most patients with a positive FIT screening result, sooner is probably better for follow-up colonoscopy.” – by Adam Leitenberger
Disclosures: Corley reports he has received grant support from Wyeth/Pfizer. Inadomi reports he has received grants from NinePoint Medical.